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/*
* Copyright (C) 2021-2022 Yomichan Authors
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
/**
* Class used for loading and validating media during the dictionary import process.
*/
class DictionaryImporterMediaLoader {
/**
* Attempts to load an image using an ArrayBuffer and a media type to return details about it.
* @param {ArrayBuffer} content The binary content for the image, encoded as an ArrayBuffer.
* @param {string} mediaType The media type for the image content.
* @param {Transferable[]} [transfer] An optional array of data that should be transferred in `postMessage` calls.
* When the resulting promise resolves, this array will contain the `content` object.
* @returns {Promise<{content: ArrayBuffer, width: number, height: number}>} Details about the requested image content.
* @throws {Error} An error can be thrown if the image fails to load.
*/
getImageDetails(content, mediaType, transfer) {
return new Promise((resolve, reject) => {
const image = new Image();
const eventListeners = new EventListenerCollection();
const cleanup = () => {
image.removeAttribute('src');
URL.revokeObjectURL(url);
eventListeners.removeAllEventListeners();
};
eventListeners.addEventListener(image, 'load', () => {
const {naturalWidth: width, naturalHeight: height} = image;
if (Array.isArray(transfer)) { transfer.push(content); }
cleanup();
resolve({content, width, height});
}, false);
eventListeners.addEventListener(image, 'error', () => {
cleanup();
reject(new Error('Image failed to load'));
}, false);
const blob = new Blob([content], {type: mediaType});
const url = URL.createObjectURL(blob);
image.src = url;
});
}
}
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